JPS633548Y2 - - Google Patents

Description

[Detailed description of the invention] This invention uses engine negative pressure to double the pedal force applied to the master cylinder and transmits the reaction force from the master cylinder to the input rod via the reaction disk. Relating to power devices.

As a conventional negative pressure booster for a master cylinder, there is one shown in FIG. 1, for example.

In FIG. 1, reference numeral 1 denotes an input rod to which depressing force from the brake pedal is applied. A plunger 2 is attached to the tip of the input rod 1 with a power piston 3 inserted therein, and a reaction disk 5 is attached to the tip of the plunger 2. An output rod 6 is provided with an interposition.

A master cylinder 7 is attached to the front shell side of the negative pressure booster having such a structure, and the output rod 6 of the negative pressure booster is in contact with the primary piston 8 of the master cylinder 7. It is being assembled.

However, in such a conventional negative pressure booster, the size of the protrusion formed at the center of the power piston 3 is limited, so the diameter of the reaction disk 5 provided at the center is increased. However, the contact area of the power piston 3 with respect to the reaction disk 5 is small, and therefore the load burden per unit volume of the reaction disk 5 becomes large. There was a problem with reduced durability.

In addition, since an outprod 6 is required to receive the reaction force of the primary piston 8 of the master cylinder 7, the axial length of the entire device when the master cylinder 7 is installed is reduced by the provision of the output rod 6. There was also the problem that the installation space for the negative pressure booster in the engine room increased.

The present invention was developed in view of these conventional problems, and it is possible to increase the diameter of the reaction disk that receives the reaction force from the master cylinder, and to reduce the axial dimension when the master cylinder is installed. It is an object of the present invention to provide a negative pressure booster for a master cylinder which is designed to save installation space.

In order to achieve this objective, the present invention incorporates a reaction disk into the primary piston of the master cylinder, and has a structure in which the input rod is directly opposed to this reaction disk. This made it possible to use a horizontal disk, lowering the load per unit volume and improving the durability of the reaction disk, and eliminating the need for an output rod, allowing the device to be made more compact with the master cylinder attached. It is something.

Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 2 is a sectional view showing an embodiment of the present invention with a master cylinder attached.

First, to explain the configuration, 1 is the input rod to which the pedal force from the brake pedal is applied.
Power piston 3 is at the tip of input rod 1.
A plunger 2 slidably provided in a shaft hole formed in the center of the power piston 3 is fitted with a diaphragm 13 that partitions a chamber formed by a front shell 11 and a rear shell 12 into a negative pressure chamber A and an atmospheric chamber B. is attached.

Also, a spring 14 is attached to the input rod 1.
A, 14b and a valve seat 15 support the valve seal 16, and when the input rod 1 moves forward and comes into contact with the valve seat 17 formed on the power piston 3, the valve seal 16 is connected to the negative pressure chamber A and the atmosphere. Separates communication with room B.

Furthermore, when the input rod 1 moves forward, only the plunger 2 moves forward with the valve seal 16 in contact with the valve seat 17, and by separating the right end surface of the plunger 2 from the valve seal 16, the valve introduces outside air into the atmospheric chamber B. The structure is realized.

On the other hand, a reaction disk 18 is attached to the end of the primary piston 10 of the master cylinder 7 assembled on the front shell 11 side. It has a diameter of
The plunger 2 of the negative pressure booster is combined with the reaction disk 18 in a facing state. or,
In order to prevent the reaction disk 18 from coming off from the primary piston 10, a donut-shaped disk 19 is interposed on the outer periphery of the reaction disk 18, which is the contact surface of the plunger 2.
Cover 2 fitted to the outer periphery of the right end of master cylinder 7
The reaction disk 18 incorporated in the master cylinder 7 is prevented from coming off from the primary piston 10 by engaging with the inner edge of the cylinder 7.

In addition, the master cylinder 7 is the primary piston 1
A secondary piston 21 is slidably provided next to the master cylinder 7, return springs 22 and 23 are provided between the primary piston 10 and the secondary piston 21, and between the secondary piston 21 and the chamber end. A reservoir tank 24 storing brake fluid is provided at the top.

Next, the operation of the embodiment shown in FIG. 2 will be explained.

First, the master cylinder 7 for the negative pressure booster
When assembling, since the reaction disk 18 is assembled into the primary piston 10 of the master cylinder 7 as shown in the figure, the master cylinder 7 can be directly assembled to the plunger 2 attached to the tip of the input rod 1. Since no output rod is required, the overall size of the device with the master cylinder 7 assembled can be reduced, and the space of the device in the engine room can be saved.

Next, to explain the negative pressure boosting operation by depressing the brake pedal, first, the negative pressure chamber A, which is in a vacuum state due to engine negative pressure in the initial state, is connected to the communication passage 3a of the power piston 3 and the valve seal 16 in the open state. It is in a state where the flow path is opened and communicated with the atmospheric chamber B.

When the input rod 1 moves forward in this state,
The valve seal 16 is the valve seat 17 of the power piston 3
The negative pressure chamber A and the atmospheric chamber B, which were in contact with each other and communicated via the communication path 3a, are partitioned off.

When the input rod 1 moves further after this partition, only the plunger 2 moves forward with the valve seal 16 in contact with the valve seat 17, and the inside and outside of the valve seal 16 communicate with each other, and outside air is introduced into the atmospheric chamber B. .

Therefore, the power piston 3 is connected to the diaphragm 13
It is pushed by the force caused by the pressure difference between the negative pressure in negative pressure chamber A and the atmospheric pressure in atmospheric chamber B, which are partitioned by .

Due to this negative pressure boosting operation by valve switching based on the advance of the input rod 1, the tip of the plunger 2 is pressed against the reaction disk 18 at the initial stage of depression of the brake pedal, and the tip of the plunger 2 is pressed against the reaction disk 18, The plate 19 and the power piston 3 are in contact with the reaction disk 18 from the beginning, and the reaction disk 18 is also pushed by the power piston 3 via the donut-shaped disk 19, thereby achieving a predetermined boost ratio. The pedal force acting on the primary piston acts on the primary piston, and as a matter of course, the pedal force acting on the primary piston 10 via the reaction disk 18 becomes a reaction force on the plunger 2 and the power piston 3 via the reaction disk 18. As the primary piston 10 moves forward by such a negative pressure booster, the liquid in the liquid chamber between it and the secondary piston 20 is pressurized, and the pressurization of the liquid causes the secondary piston 21 to move forward as well. The liquid in the left chamber will now be pressurized.

FIG. 3 is a cross-sectional explanatory view of another embodiment of the present invention, showing the assembly part of the master cylinder to the power piston of the negative pressure booster. A feature is that a member is provided to prevent misalignment.

That is, the reaction disk 1 incorporated in the end of the primary piston 10 of the master cylinder 7
8 is followed by a stepped cylindrical member 25, which is shown in FIG. The small diameter shaft portion 25a is opposed to the small diameter shaft portion 25a.

By providing the stepped cylindrical member 25 at the center of the contact surface side of the reaction disk 18 in this way,
Even if the primary piston 10 of the master cylinder 7 is misaligned with respect to the plunger 2, the reaction disk 18 can be reliably pressed through the stepped cylindrical member 25 by the forward movement of the plunger 2, resulting in slight misalignment. It is possible to prevent malfunction due to

Next, to explain the effect of the present invention, a reaction disk that transmits the reaction force from the master cylinder to the power piston and input rod is assembled to the primary piston in the master cylinder, and the plunger on the input rod side is directly opposed to this reaction disk. This makes it possible to use a reaction disk of sufficient size according to the diameter of the primary piston in the master cylinder without being constrained by the shape of the shaft of the power piston in the negative pressure booster. By increasing the reaction force area of the reaction disk during operation, the load applied per unit volume of the reaction disk can be reduced and the durability of reaction disks made of rubber etc. can be greatly improved. .

In addition, since the input rod side of the negative pressure booster is directly opposed to the reaction disk built into the primary piston of the master cylinder, an output rod is no longer required, and the negative pressure is increased by the amount that the output rod is no longer needed. The axial dimension when the master cylinder is assembled to the booster can be reduced, and the installation space when installing the negative pressure booster in the engine room can be saved.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing a conventional example, Fig. 2 is a cross-sectional view showing an embodiment of the present invention, and Fig. 3 is a cross-sectional view showing another embodiment of the present invention with respect to the integrated part of the reaction disk. , FIG. 4 is a perspective view of the stepped cylindrical member in the embodiment of FIG. 3. 1...Input rod, 2...Plunger,
3...Power piston, 7...Master cylinder,
10...Primary piston, 11...Front shell, 12...Rear shell, 13...Diaphragm, 14a, 14b...Valve spring, 1
5... Valve seat, 16... Valve seal, 1
7... Valve seat, 18... Reaction disk, 1
9...Disk, 20...Cover, 21...Secondary piston, 22, 23...Return spring, 24...Reservoir tank, 25...Stepped cylindrical member, 25a...Small diameter shaft portion, A...Negative Pressure chamber, B...
...Atmospheric chamber.

Claims (1)

[Scope of Claim for Utility Model Registration] A vacuum for a master cylinder that has a structure in which the reaction force from the master cylinder is transmitted via a reaction disk to the input rod on which pedal force acts and the power piston that operates due to the differential pressure between atmospheric pressure and engine negative pressure. A negative pressure booster for a master cylinder, characterized in that the reaction disk is incorporated into the primary piston of the master cylinder, and the tip of the input rod is opposed to the reaction disk.